The assembly of annular shear accelerometers entails the radial compression of an annular crystal element between a radially outer annular mass element and, typically, a radially inner annular force ring. The nested combination of the crystal element, the mass element, and the force ring is rigorously secured to a suitable mounting structure such as a cylindrical post, bolt, or functionally similar device that extends axially through the combination and abuts the radially inner surface of the force ring. Applicant is aware of two known methods for effecting this securement while providing the forementioned radial compression.
The first is to position around the mass element a radially outer ring having a tapered, convergent inner surface. The outer ring is then pressed in an axial direction so that its inner surface radially compresses the combination. In this method, the outer ring in effect becomes an extension of the mass element, and tolerancing is made more critical as a result of that effect.
The second method uses an outer ring or sleeve made of a shape-memory alloy such as that sold under the trademark TINEL. The ring is positioned around the mass element while still in its low-temperature phase, and shrinks in its high-temperature phase to radially compress the nested combination. The use of this method, in addition to requiring an expensive alloy, requires either cryogenic storage of the alloy or the additional operation of heating the ring after it is positioned around the mass element. In either case, disassembly of the accelerometer is either an impracticably expensive process, or is at least partially destructive.